What Is Global Server Load Balancing?

Global server load balancing (GSLB) refers to the intelligent distribution of traffic across server resources located in multiple geographies. The servers can be on premises in a company’s own data centers, or hosted in a private cloud or the public cloud.

Disaster recovery is the primary reason that many companies deploy server resources at multiple locations. In the most common configuration, data is served from one active location but duplicated at one or more standby (passive) locations that serve it only if the active site fails. The global server load balancer’s role in this case is to detect the failure at the active site and automatically divert requests to the standby sites.

A major reason to choose an active‑passive scheme is that there is no need to synchronize data across sites in real time; changes at the active site can be distributed to the passive sites using a simpler batch method and cheaper out‑of‑band connections. If you maintain multiple active sites serving the same content – and some of the benefits of GSLB in the following list emerge only if you do – then synchronizing the sites in real time becomes important.

Benefits of global server load balancing include the following:

Reliability and availability – GSLB can be used to improve website reliability and availability in the face of server or network outages. If a power outage hits the northeastern U.S. after a snowstorm, for example, the load balancer can direct traffic away from resources hosted there to resources hosted in other parts of the country.

Performance – Delivering content from a server that is closer to the requesting user minimizes network latency and the likelihood of encountering network problems. For instance, directing requests from Australian users to servers in Sydney instead of servers in New York shortens the distance packets must travel by about 10,000 miles (16,000 km) one way.

Satisfying regulatory and security requirements – For many highly regulated industries like defense, telecommunications, and healthcare, global server load balancing enables network architects to service a global user base in a manner that complies with government regulations. For example, a global server load balancer can be configured to forward requests to data centers in Canada only if they come from Canadian users, not users in any other countries.

Delivering localized content – By using information about the geographical location of users, global server load balancers can forward requests to servers that host content customized for relevance in the user’s country and written in the national language.

While it is possible to implement global server load balancing in house, the challenges of keeping data synchronized at multiple sites – and load balancing across the sites efficiently – are not trivial. Many companies obtain their GSLB solution from a managed DNS provider such as Akamai or Amazon Route 53. NGINX Plus does not provide GSLB capabilities directly, but its sophisticated load‑balancing algorithms, server health checks, and other features make it ideal for use at the on‑premises or cloud data centers to which global server load balancers are directing traffic. Specialized modules in NGINX Plus make it easy to capture information about client location and use it in the local load‑balancing decision.

As a software load balancer, not only is NGINX Plus less expensive than hardware‑based solutions with similar capabilities, it can be deployed in the public cloud as well as in private data centers, whereas cloud infrastructure vendors generally do not allow customer or proprietary hardware load balancers in their data centers.